1. Technical Field
The present invention relates to: a method for identifying by spectral analysis a colorant used in generating a color image; and a colorant identification apparatus.
2. Description of Related Art
With the advancement of image forming apparatuses, generation of image recorded matter such as a document obtained by recording an image on paper becomes easy. Thus, generation of unauthorized image recorded matter such as copied matter of a document recording secret information and forged matter of a banknote or securities also becomes easy like. Meanwhile, colorants such as ink and toner used in recording images have mutually different compositions in accordance with the difference of the manufacturers or the like of image forming apparatuses and colorants. Thus, when the colorant used in the image recorded matter is analyzed, the kind of colorant is allowed to be identified in correspondence to the difference of the manufacturers or the like of image forming apparatuses and colorants. Then, when the kind of colorant is identified, an image forming apparatus used in generation of unauthorized image recorded matter is allowed to be identified and this may contribute to investigation of the circumstances of generation of the unauthorized image recorded matter.
In the conventional art, Raman spectroscopy is used as a non-destructive method for analyzing a sample. Japanese Patent Application Laid-Open No. 2006-300808 describes that toner is adopted as a target of Raman spectroscopy. When Raman scattered light from colorants of mutually different kinds is measured, the obtained Raman spectra are different from each other. Thus, when the Raman spectrum of a colorant is investigated, the colorant is allowed to be identified.